1. Field of the Invention
The present disclosure relates to liquid crystal display technology, and more particularly to a color filtering array substrate and the manufacturing method thereof.
2. Discussion of the Related Art
Liquid crystal displays (LCDs) typically are characterized by attributes including thin, power-saving, and low radiation. Thus, the LCDs are widely adopted by a plurality of electronic devices, such as mobile phones, PDA, digital cameras, displays of personal computers or notebooks.
Currently, most of the LCDs are backlight-type LCDs. Generally, the LCDs include a housing, a liquid crystal panel and a backlight module arranged within the housing. The liquid crystal panel includes a color filtering array substrate, a Thin Film Transistor (TFT) Array Substrate, and a liquid crystal layer arranged therebetween. By applying driving voltages toward the two substrates to control the alignment of the liquid crystal, the light beams from the backlight module are reflected so as to display images. As the liquid crystal does not emit light beams itself, the backlight module is needed to provide the light source so as to display images. Thus, the backlight module is a key component of the LCDs. Generally, backlight modules can be classified into edge-type and direct-lit type according to the incident locations of the light source. Regarding the direct-lit type backlight module, the Cold Cathode Fluorescent Lamp (CCFL) or Light Emitting Diode (LED) are arranged behind the liquid crystal panel to form a surface light source. With respect to the edge-type backlight module, the LED light bars are arranged at lateral rear sides of the liquid crystal panel. The light beams emitted from the LED light bar enter one side of the Light Guide Plate (LGP). After being reflected and diffused, the light beams emit out from the light emitting surface and then operates as the surface light source of the liquid crystal panel.
Electro-Static discharge (ESD) is a key factor of the manufacturing of the TFT array substrate. Referring to FIGS. 1 and 2, a gate metallic layer (M1) 100 and a source/drain metallic layer (M2) 200 are interleaved or overlie to form a capacitor, which adopts the insulation layer to be the dielectric, such as SiNx. In the manufacturing process, the gate metallic layer 100 and the source/drain metallic layer 200 accumulate charge such that the voltage is generated therebetween. When the voltage equals to a breakdown voltage of the capacitor, the voltage may pass through the insulation layer 300 between the gate metallic layer 100 and the source/drain metallic layer 200. Under such circumstance, the gate metallic layer 100 and the source/drain metallic layer 200 are short connected and result in a general ESD effect. Such ESD effect may cause the liquid crystal panel malfunction.
The electrical field intensity (E) between two ends of the capacitors is calculated by the equation of: E=U/d, wherein U represents a voltage difference between the two ends, and D represents the distance between the two ends. When the electrical field intensity (E) is too large and equals to the breakdown voltage of the capacitor, the ESD effect may occur. Thus, decreasing the electrical field intensity (E) is one solution to avoid the ESD effect. However, the voltage difference (U) between the gate metallic layer 100 and the source/drain metallic layer 200 is unpredictable and uncontrollable.
Recently, one new solution named “Color Filter on Array (COA)” is proposed, which relates to directly bonding the color filtering array substrate onto the TFT array substrate. As such, the alignment of the TFT array substrate and the color filtering array substrate can be controlled. As shown in FIG. 3, the manufacturing process includes the following steps. A first metallic layer is arranged above the glass substrate, and an insulation layer is formed above the first metallic layer. An amorphous silicon layer is formed above the insulation layer. An active layer is formed above the amorphous silicon layer. A second metallic layer is formed above the active layer. A first protective layer is formed above the second metallic layer. A color filtering layer is formed above the first protective layer. A second protective layer is formed above the color filtering layer. A transparent conductive layer is formed above the second protective layer so as to form the color filtering array substrate. Afterward, the color filtering array substrate is assembled with an opposite arranged substrate with liquid crystal filled therebetween to form the liquid crystal panel. It is to be noted that the opposite arranged substrate does not include the color filtering array substrate.
However, the above configuration may result in electrostatic effect in the interleaved portions between the gate metallic layer and the source/drain metallic layer, and which will shorten the lifetime of the liquid crystal panel.